Even though post-exertional malaise is a hallmark feature of ME/CFS, exercise programs are often prescribed with little thought to the effect they may have on patients. The panel of experts for the ME/CFS clinical consensus document(1) stressed that a thorough evaluation of patients and their total illness burden, optimizing medical management, and a careful evaluation of pain generators and risk factors must be done before even considering an exercise program. As much care must be taken in prescribing appropriate exercise for ME/CFS patients as in prescribing pharmaceuticals.(5)